Estimated Load Feedforward instead of Voltage Integrator for Phase-Shifted Full Bridge Converter to Enhance Transient Response

A novel control algorithm for the phase-shifted full bridge converter is proposed that employes proportional controller for the voltage loop and proportional-integral controller for the current loop. Besides, estimated load feedforward is adopted using the filtered primary current. Moreover, the voltage integrator is removed to avoid its deterioration to transient response. In such a way, both infinity open-loop dc gain and attenuated output impedance are achieved, leading to precise regulation and fast response. Only output voltage and primary current are sensed, whose sampling-gain drifts are tolerable. Simulation and experiment results verify the methodology.